int
load_macho( const char *image_name )
{
load_command_t cmd;
mach_header_t hd;
int i, pos, fd;
if( (fd=open(image_name, O_RDONLY)) < 0 )
fatal_err("opening %s", image_name );
if( !is_macho(fd) ) {
close( fd );
return 1;
}
if( read(fd, &hd, sizeof(hd)) != sizeof(hd) )
fatal("failed to read Mach-O header");
pos = sizeof(hd);
for( i=0; i<hd.ncmds; i++, pos+=cmd.cmdsize ) {
if( pread(fd, &cmd, sizeof(cmd), pos) != sizeof(cmd) )
break;
lseek( fd, pos, SEEK_SET );
if( cmd.cmd == LC_SYMTAB )
continue;
/* printm("\nLoad-CMD [%d]: %ld\n", i, cmd.cmd ); */
switch( cmd.cmd ) {
case LC_SEGMENT:
read_segment( fd );
break;
case LC_THREAD:
case LC_UNIXTHREAD:
read_thread( fd );
break;
}
}
close( fd );
return 0;
}
int macho_bootstrap(func_t *funcs)
{
int x, y;
// We need a pointer anywhere onto the stack
char *s = __builtin_alloca(0);
// Let's find the very top of the stack
while(is_ptr_valid((size_t)s + 1))
s++;
for(x = 0; x < 10000; x++)
{
// Walk down the stack, one byte at a time
size_t *ptr = (size_t *)(s - x);
// Do we have a valid pointer?
if(!is_ptr_valid((size_t)ptr) || !is_ptr_valid(*ptr))
continue;
// Page-align the pointer
size_t addr = *ptr & ~(PAGE_SIZE - 1);
// Walk backwards one page at a time and try to find the beginning
// of a mach-o file
for(y = 0; y < 100; y++)
{
if(is_ptr_valid(addr) && is_macho(addr) && macho_parse((void *)addr, funcs))
return 1;
addr -= PAGE_SIZE;
}
}
return 0;
}
